This invention relates to automotive radar systems and more especially but not exclusively it relates to automotive cruise control systems which use radar.
In recent years there has been much interest in the development of an adaptive cruise control system for automobiles, more especially for motorway use. Such a system involves measuring the speed of a host vehicle in which the system is fitted, and the distance of the host vehicle from a vehicle in front in the same lane. Cruise control then operates to control the speed of the host vehicle in order to maintain a safe distance from the car in front and to ensure that a predetermined maximum speed is not exceeded. An obvious method of measuring the speed and/or the range of the car in front is to use radar. It is clear that radar suitable for this purpose must not only have very good angular resolution, since it must be able to discriminate with confidence at long range between a vehicle in front in the same lane as the host vehicle, from a vehicle in front in an adjacent lane, but moreover must have very accurate radar boresight alignment with the direction of travel of the host vehicle.
Good angular resolution can be provided using known narrow beam radar techniques but hitherto the necessary boresight alignment accuracy has been much more difficult, if not impossible to achieve reliably and in a relatively simple manner which lends itself to use in the mass production of automobiles.